Sebastian Silva, Tunde Adebimpe and Kristen Wiig star in a story of modern living that takes a dark turn

Premiering Saturday as part of the Sundance Film Festival’s Next section, “Nasty Baby” starts as a casual comedy of hipster manners and modern lifestyles, but takes a rather shocking turn to something stranger and more disturbing.

On the phone for an interview shortly before the start of the festival, Sebastian Silva, the film’s Chilean-born, Brooklyn-based writer, director and co-star, admitted it’s his own apartment that makes up the film’s main location – “It’s scary because you can see the address, right?” he said.

Though he may be vaguely concerned with people showing up on his doorstep, what he says he is not concerned about is spoiling the film’s shifts in tone -- in fact he hopes audiences have some sense of what they’re in for.

“It’s going to lead to a lot of confusion, which I really like,” he said, “I don’t think you really know what it is, it just feels like a very real, naturalistic story of friends in Brooklyn and then there’s the thriller part.”

In the film, Silva plays Freddy, an artist who along with his boyfriend Mo wants to have a baby together; their friend Polly agrees to carry the child. There are complications as to which of the men will father the baby, causing tension between them. At the same time, the three of them are growing increasingly bothered by an abrasive neighbor, a situation which escalates further than they could ever imagine.

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Freddy’s boyfriend Mo is played by Tunde Adebimpe, a member of the band TV On The Radio previously seen onscreen in Jonathan Demme’s “Rachel Getting Married.” Their friend Polly is played by Kristen Wiig, in a low-key performance different from her outsized comedic character work. Both were introduced to Silva via his friend Alia Shawkat, the actress best known from “Arrested Development” and who also appears in the film a small role.

“Nasty Baby” is the fifth of Silva’s six films to play at Sundance. When he was last here in 2013 it was with two films, both featuring Michael Cera, the blissed-out road comedy “Crystal Fairy” and the bum-trip psychological horror of “Magic Magic.” Silva would win the festival's World Cinema directing prize for “Crystal Fairy” and the film went on to earn two Spirit Award nominations.

Courtesy of the Sundance Film Festival

Kristen Wiig in a scene from 'Nasty Baby,' which is premiering as part of the 2015 Sundance Film Festival.

Kristen Wiig in a scene from 'Nasty Baby,' which is premiering as part of the 2015 Sundance Film Festival. (Courtesy of the Sundance Film Festival)

In a way, “Nasty Baby” fuses the impulses of those two films into one. There are scenes of warmth and gentle humor as the three friends go about forming a makeshift family, taking a dark turn as things go from bad to worse with the neighbor.

Silva, 35, had never acted before, and so he knew that casting himself in one of the leads in a film that mixed and matched between scenes of intimate emotions and deep discomfort could lead to challenges.

“It just made sense that I would do it and I felt like I wanted to try it,” he said. “This is my sixth feature film, and it’s not that it’s getting old making movies, but the more different the process is, the more fun I have too.

“To be honest, I thought what if the scenes don’t work out, what if my acting is pathetic and I’m embarrassing myself?”

That sense of facing down the unknown runs through “Nasty Baby” and is also part of the reason why Silva doesn't worry about audiences knowing too much about the movie. Even he doesn’t entirely understand yet what it’s really about.

“‘Nasty Baby’ is really the only movie I’ve done so far that I’m not really sure why I made it,” Silva said. “I think it’s going to be fun to have Q&As about the movie. I don’t know what to make of the movie and I really like that.

“When you ask me about ‘Magic Magic’ or ‘The Maid’ or ‘Crystal Fairy’ or any of my movies I’ve made, I really know what the moral conclusion is,” he said. “And this movie I really don’t, I cannot wrap my head around it.”